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. @uitrit tats @anni @fitta GEORGE W.. eno WN, or noeKFo'nD, i ILLINOIS. Letters Patent No.473,29-.9, dated January A14, 1868.

IMPROVEMENT IN SPIROMETERS.

TO WHOM IT MAY CONCERN:

Be it known that I, GEORGE W. BROWN, of Rockford, in the county of Winnebago, and State of Illinois, have invented a new and improved Spiromctcr, for measuring the breathing capacity of the human lungs in cubic inches, with a view to their intelligent medical treatment, if diseased. v

My invention consists of a reservoir, A, made of tin plate, eight and one-half inches long, four and one half inches wide, and thirteen and one-half inches high, with a water-tight bottom, the reservoir open only at the top. A tube, B, three-eighths of an inch in diameter, is passed through the middle of the front side, at the bott-om of the reservoir; thence passingr to the inner centre at the bottom, is bent at a right angle, and rises to the surface, level with thetop. This tube projects three-fourths of an inch outside of the instrument,-to receive an elastic tubing, one yard -in length, marked C, through which the breath is expelled into the instrument. A drum, measuring four b-y eight inches in the inside, and thirteen inches high, is also made of tin plate, closed at the top, open at the bottom, and made air-tight. This is inserted 'in the reservoir, open end down. Guides, E E, are fixed at each end, and at the top and middle of" the end of the reservoir, one-eighth'of au inch in diameter, and rising above the top of the reservoir twelve inches, attached by being slipped into open sockets,

F F, thc size of the guides, and closed at thebottom, to prevent the guides dropping through out of place. They are connected at the top by a cross-bar, X, to sustain the upper ends of the guides and keep them equidistant from each other. I usually'make the guides and cross-bar X of continuous w'ire, bent at the corners at right angles, as shown in the diagram. Eyes, G G, are soldered to the top of the drum, projecting halt` an inchv at each end from the drum, and` perforated ,with a hole, one-eighth of an inch in diameter, through which the guides are slipped, when the drum is in place, into the socketsF F; their object, to keep the drum perpendicular to the plane of the reservoir, when in use, and prevent it from careening. An index,'I-I, to indicate the amount of air in cubic inches which the lungs can expel, is attached to the top and front side ofthe drum, and midway of the same, and is made of a strip of tin plate, one and one-quarter inch wide, and thirteen'inches long, soldered to the top of thedrum, at the middle of the front'side. Projecting forward half an inch from the edge of the drum, it is bent down at right angles with the top, and parallel with the sides, so that when the drum is' in place it drops down in front of the reservoir, to near the bottom of the intrumcnt. -On this I paste a printed paper index, divided into-inches, half, quarter, and one-eighth inches. Each `quarter of an inch onthe scale indicates eight inches in the drum. The smaller numbers are at the top, increasing eight inches for each quarter of an inchmarked o n the scale, until it reaches the bottom. The edges of the tin plate onlwhich the printed paper slip is pasted are bent forward, to prevent the wear of the lines and iiguresagainst the shield, to be next described. A shield, I,. to-cover the index, protecting it from injury, and shielding the numbers not indicated bythe breath-measure from sight, extends from within one inch ofthe top of the reservoir to the bottom of the same, wide enough, and projecting forward from the drum far enough, to admit the free passage of the index without friction. I make this of `tin, two and one-half inches wide, and twelve inchesA long, with halt' an inch" on cach cdge bent backwards at right angles, and soldered to the reservoir, leaving a cavity extending from within one inch of the top to the bottom ot' the instru1nentaiid, on the front side, one and one-halfl inch wide and hali'ian inch deep. When the drum and index are in place and at rest, the zero ot' the `index isv level with the top edge of the shield. A A

i When in use, the reservoir is filled with iva-ter tofwithin two inches of the top of the saine. The drumis inserted in the water, the open cnd do\vn.' The guides are passed through the eyes on the drum, and thence pressed tightly into Ythe sockets. The lunes are inflated'to their full capacity. The end of .the elastic tube C,

Ain which a three-eighth glass tn be is inserted, is placed, betweeirthe lips, and the breath is gradually pressed through the tubes B and C, abovethe top of the water in thc reservoir, into thevacuum in the top of the airtight drum. The drum,which had before settled into place, rises, carrying with it the index', and on a level with theiop of the shield is read, in figures, the number of cubic inches of air expelled from the lungs, and

'indicating their extreme breathing capacity.

I am aware thatspirometers, and the general principles of the reservoir and drum described herein, have long been in use. I thereforedisclaim the invention of such appliances, apart from my specific improve4 ments; but

I claim herein qs new and off-'my invention, andv desire to secure by Letters Patent- 1. The arrangement of spirometers and indexvH, and shield-f1, in the manner specified, und for the purpose as describedherein.

y2. The nietitube B, which rises through the Water in the reservoir A.

3- The arrangement of the guides EE and eyes FF with sprometcr, for the nso and in the manner herein described and Set forth.

, G. W. BROWN.

Witnesvses:

IW.l WfWooD. H. lM. WEBB. 

